Update headerapi.md

Author: n123git

headerapi.md

@@ -8,3 +8,6 @@ title: Header API
 
 ## Misc
 * `utf8` - A global var that determines whether to use `cp932` (JP ver.) or `UTF-8` (International ver.). True by default. 
+* `panic()` - A function used to signal warnings - this is usually used by the API to signal errors, more can be found in the Error section.
+
+## Errors